1. Field of the Invention
The present invention generally relates to a thin film transistor (TFT) array substrate and the repairing method thereof. More particularly, the present invention relates to a TFT array substrate and the repairing method thereof having high yield of repairing.
2. Description of Related Art
In recent years, the multimedia and the related devices are developed extensively due to the leaps and bonds of the semiconductor device or the display device. As to the display device, the cathode ray tube (CRT) were broadly used in the past because of the good display quality and the low price. However, the cathode ray tube has the disadvantages of large size, high power consumption and high environmental concerns. Since the liquid crystal display (LCD) has the advantages of light weight, small size, thin thickness, low power consumption, low radiation and environmentally, the cathode ray tube is being gradually replaced by the liquid crystal display. In general, the thin film transistor (TFT) LCD is most popularly applied in the LCD device.
Conventionally, the liquid crystal display (LCD) have dot defect or line defect problems. In general, a dot defect is generated due to the abnormal electrical conduction between the top and bottom electrodes of the pixel capacitor by particle or defect. Moreover, the dot defect may also be generated due to the abnormal electrical conduction at the intersection of scan line and data line, thus, a white spot or a dark spot is formed in the intersection. Usually, a line defect is generated by the breaking of scan line or data line. The yield of a liquid crystal display (LCD) is quite dependent on the dot defect or line defect that typically generate during the manufacturing of the LCD. Therefore, the repairing of the dot defect or line defect to further improve the display quality is very important. Hereinafter, a conventional repairing technology will be described with reference to FIG. 1.
FIG. 1 is a drawing schematically illustrating the conventional laser chemical vapor deposition (CVD) repairing method. Referring to FIG. 1, a conventional pixel structure 100 includes at least a scan line 102, a signal line 104, a thin film transistor (TFT) 106 and a pixel electrode 108. The thin film transistor (TFT) 106 includes a gate 106a, a channel layer 106b and a source/drain 106c, in which the gate 106 is electrically connected to the scan line 102, and the source/drain 106c are electrically connected to the signal line 104 and pixel electrode 108 respectively.
Since the scan line 102 is a portion of the first metal layer M1, and the signal line 104 is a portion of the second metal layer M2, the scan line 102 and the signal line 104 are electrically insulated from each other by a first dielectric layer (or called gate isolation layer). Moreover, a second dielectric layer (or a protection layer) may be formed to cover the signal line 104. However, the intersection of the scan line 102 and the signal line 104 may be shorted abnormally due to the faulty the dielectric layer, for example, due to contamination by impurity or particles. Thereafter, repairing of the abnormally shorted intersection is required. A conventional repairing method is to cut both ends of the signal line 104 of the shorted intersection shown by the dotted line in FIG. 1. Then, two repairing openings 110 are formed by irradiating laser on the second dielectric layer. Thereafter, a repair line 112 is formed to reconnect the cut signal line 104 via the opening 110 by performing a laser chemical vapor deposition (CVD) process. Therefore, the abnormally shorted intersection is repaired by a conventional method.
FIG. 2 is a cross-sectional view of the intersection repaired by a conventional laser repairing method. Referring to FIG. 2, it is noted that the data line 104 may get damaged by laser beam when repairing in the openings 110. Since a conventional data line 104 is usually comprised of molybdenum, aluminum and molybdenum multilayer metal structure, and the melting point of aluminum is less than that of the molybdenum. Therefore, after the data line 104 laser is irradiated by the laser beam to form the opening 110, the aluminum metal layer will get vaporized resulting in a formation of a data line with bent profile A as shown in FIG. 2. It is to be noted that, the repair line 112 formed by laser chemical vapor deposition (CVD) process may be susceptible to breakage near the bent section at the bent profile A, and thus the repairing technique using laser CVD process is accordingly not desirable.